Frey, William H. 2002. "Three Americas: The Rising Significance of Regions." Journal of the American Planning Association, 68(4): 349-355.
The results of the 2000 Census show the increasing importance of regional differences for understanding America's racial and demographic landscape. Well-worn local labels such as urban, suburban, and rural are becoming less descriptive of lifestyles, racial profiles,and age structures than distinctions that separate sets of states into three regions: the suburb-like "New Sunbelt," the racially diverse "Melting Pot," and the slow-growing, aging "Heartland." These regional divisions are rooted in the somewhat distinct redistribution patterns of immigrant minorities, who have concentrated mostly in coastal areas, and streams of largely white domestic migrants, who have gravitated to newer, economically prosperous areas in the Southesast and West.